Image reading apparatus and copying apparatus having means for radiating visible and non-visible light, image processing apparatus having means for discriminating a specific orginal and image processing method therefor

ABSTRACT

This invention has as its object to reduce the apparatus scale by simplifying the arrangement of an image reading apparatus for radiating light including both visible and non-visible components, and detecting light obtained from a predetermined image, and provides an image reading apparatus which has illumination means for simultaneously radiating both light including a visible component and light including a non-visible component, and detection means for detecting light obtained from a predetermined image in accordance with the light radiated from the illumination means, including filter means which can be switched in accordance with whether the visible or non-visible component is radiated from the illumination means onto the predetermined image, and control means for controlling a switching operation of the filter means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image reading apparatus, a copyingapparatus, and an image processing apparatus, which have a function ofdiscriminating a specific original.

2. Related Background Art

Conventionally, various methods associated with recognition of, e.g., aspecific original, have been proposed.

Methods of recognizing that an image pattern of an original is definedby a line image, or recognizing a color tone of an image original, havealso been proposed.

Furthermore, in another method, a specific mark is printed with afluorescent ink, which reflects visible light upon radiation-ofultraviolet rays onto a specific original itself, so as to identify anoriginal print from copies on the basis of the presence/absence of thefluorescent mark.

However, when these methods are applied to a copying machine, it isdifficult to detect a specific original which is located at an arbitraryangle with respect to an arbitrary position on an original table of thecopying machine, and hence, it is difficult to prevent forgery.

Even when line image information or a color tone of an original isdetected, some normal originals may exhibit equivalent characteristicsas those of a specific original, and a normal original may beerroneously determined to be a copy-inhibited original.

Furthermore, in the copying machine which detects a specific original onthe basis of the presence/absence of a fluorescent mark, both anarrangement for detecting ultraviolet rays and an arrangement fordetecting visible light for a copying operation are required, and theapparatus scale undesirably becomes very large. In addition, the levelsof the detected ultraviolet rays and visible light vary depending onindividual differences of apparatuses, and it is difficult to achieveprecise detection.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theabove-mentioned problems, and has as its object to provide an imagereading apparatus with high discrimination precision.

It is another object of the present invention to provide an imagereading apparatus which suffers less from aging.

It is still another object of the present invention to provide an imagereading apparatus which can discriminate a specific original.

It is still another object of the present invention to provide an imageprocessing apparatus and an image processing method, which candiscriminate a specific image by detecting non-visible light from apredetermined image.

It is still another object of the present invention to provide an imagereading apparatus with a simple circuit arrangement.

In order to achieve the above objects, according to a preferred aspectof the present invention, there is provided an image reading apparatuswhich comprises illumination means for simultaneously radiating bothlight including a visible component and light including a non-visiblecomponent, and detection means for detecting light obtained from apredetermined image in accordance with the light radiated from theillumination means, comprising: filter means which can be switched inaccordance with whether the visible or non-visible component is radiatedfrom the illumination means onto the predetermined image; and controlmeans for controlling a switching operation of the filter means.

It is still another object of the present invention to provide an imageprocessing apparatus, an image reading apparatus, a copying machine, andan image processing method, which have a novel function.

Other objects and features of the present invention will become apparentfrom the following description of the embodiment taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is comprised of FIG. 1A and FIG. 1B showing block diagrams of asignal processing unit according to the first embodiment of the presentinvention;

FIG. 2 is a block diagram showing an analog signal processing unit ofthe first embodiment;

FIG. 3 is comprised of FIG. 3A and FIG. 3B showing flow charts of lightamount adjustment/circuit gain control of the first embodiment;

FIG. 4 is a block diagram showing light amount control blocks of anoriginal illumination lamp;

FIGS. 5A and 5B are graphs showing the characteristics of a fluorescentink of the first embodiment;

FIG. 6 is an enlarged view of light-receiving elements of a CCD sensorof the first embodiment;

FIG. 7 is a view showing an arrangement of the CCD sensor of the firstembodiment;

FIG. 8 is a flow chart for explaining the first embodiment;

FIG. 9 is a schematic sectional view showing an arrangement of a colorcopying machine using the first embodiment;

FIG. 10 is a schematic sectional view showing an arrangement of a colorcopying machine using the second embodiment;

FIG. 11 is a schematic sectional view of an original illumination unitof an original reading apparatus using the fifth embodiment;

FIG. 12 is a graph showing the spectrum sensitivity of a visible lightsensor of the first embodiment;

FIG. 13 is a graph showing the spectrum sensitivity of the visible lightsensor of the first embodiment;

FIG. 14 is a schematic sectional view showing an original illuminationunit of an original reading apparatus using the second embodiment;

FIGS. 15A, 15B, and 15C are graphs showing the spectrum characteristicsof an original illumination lamp, and the spectrum sensitivitycharacteristics of optical filters in the second embodiment;

FIG. 16 is a schematic sectional view showing an original illuminationunit of an original reading apparatus using the third embodiment;

FIGS. 17A, 17B, and 17C are graphs respectively showing the spectralcharacteristics of an original illumination lamp, the spectralsensitivity characteristics of optical filters, and the opticalcharacteristics of a fluorescent material in the fourth embodiment;

FIG. 18 is a schematic sectional view showing an original illuminationunit of an original reading apparatus using the fourth embodiment;

FIG. 19 is a schematic sectional view showing the original illuminationunit of the original reading apparatus using the fourth embodiment;

FIGS. 20A, 20B, and 20C are graphs respectively showing the spectrumsensitivity characteristics of optical filters and the opticalcharacteristics of a fluorescent material in the fourth embodiment;

FIG. 21 is a schematic sectional view showing an arrangement of a colorcopying machine using the sixth embodiment;

FIG. 22 is a partial sectional view showing an original readingapparatus using the sixth embodiment;

FIG. 23 is a partial sectional view showing an original readingapparatus using the seventh embodiment;

FIG. 24 is a graph showing the characteristics of an infraredfluorescent agent of the eighth embodiment;

FIG. 25 is a schematic sectional view showing an arrangement of acopying machine of the eighth embodiment;

FIG. 26 is graph showing the spectrum distribution of a lamp used as alight source of the eighth embodiment;

FIG. 27 is a perspective view showing the outer appearance of a filterframe of the eighth embodiment;

FIG. 28 is a graph showing the spectrum characteristics of a visiblelight cut filter of the eighth embodiment;

FIGS. 29A and 29B are views showing originals printed with patternsusing an infrared fluorescent paint of the eighth embodiment;

FIG. 30 is a schematic sectional view showing a white shading correctionstate of the eighth embodiment;

FIG. 31 is a schematic sectional view showing an infrared shadingcorrection state of the eighth embodiment;

FIG. 32 is a CCD driving timing chart of the eighth embodiment;

FIG. 33 is a CCD driving timing chart of the eighth embodiment;

FIG. 34 is a schematic sectional view showing lamp and a shading plateof the ninth embodiment;

FIG. 35 is a graph showing the light-emission characteristics of a lightsource 670 used in FIG. 34;

FIG. 36 is a side view showing a state wherein two shading plates of thetenth embodiments are integrated;

FIG. 37 is a graph showing the characteristics of another fluorescentpaint; and

FIG. 38 is a graph showing the characteristics of still anotherfluorescent paint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

The preferred embodiments of the present invention will be describedhereinafter.

In the embodiments to be described below, the present invention isapplied to a copying machine. However, the present invention is notlimited to this. For example, the present invention can be applied tovarious other apparatuses such as an image scanner connected to acomputer.

FIG. 9 shows the outer appearance of an apparatus according to the firstembodiment of the present invention.

Referring to FIG. 9, an image scanner unit 201 performs an image readingoperation, and digital signal processing. A printer unit 202 prints outa full-color image corresponding to an original image read by the imagescanner unit 201 on a paper sheet.

The image scanner unit 201 includes a fluorescent lamp 5101 for emittinglight (ultraviolet rays) in a short-wavelength range (wavelength rangeother than visible light), which light can efficiently excite a normalfluorescent ink. FIG. 5A shows the light-emission spectrumcharacteristics of the fluorescent lamp 5101, and the reflectionspectrum characteristics of the fluorescent ink irradiated with lightfrom the fluorescent lamp 5101. The fluorescent ink has characteristicsin that it does not emit fluorescence for light components emitted froma halogen lamp 205. As shown in FIG. 5B, the fluorescent ink is excitedby only light of a specific wavelength. A mirror-surface thick plate 200is arranged on the upper surface of the image scanner unit 201. Anoriginal 204 placed on an original table glass (to be referred to as aplaten hereinafter) 203 is irradiated with light emitted from thehalogen lamp 205 or the fluorescent lamp 5101, and light reflected bythe original is guided to reflection mirrors 206, 207, and 208. Thelight then forms an image on a CCD sensor (to be referred to as a sensorhereinafter) 210 including R, G, and B 3-line CCD sensors via a lens209, and is then supplied to a signal processing unit 211 as red (R),green (G), and blue (B) components of full-color information. The lamp205 and the mirror 206 are mechanically moved at a speed V in adirection (to be referred to as a sub-scan direction hereinafter)perpendicular to an electrical scan direction (to be referred to as amain scan direction hereinafter) of the line sensor, and the mirrors 207and 208 are mechanically moved at a speed 1/2 V in the sub-scandirection, thereby scanning the entire surface of the original.

A standard white plate 5102 is arranged at a position where it isilluminated with the original illumination means when the originalillumination means is located at a reference position (to be referred toas a home position hereinafter), and is separated by the same opticaldistance from the sensor as that between the sensor and an original onthe platen. Data obtained using the plate 5102 is used as correctiondata for correcting a variation of image data read by the sensor 210when the halogen lamp 205 is used. A fluorescence reference plate 5103is arranged at a position opposite to the standard white plate 5102 inthe scanning direction of a carriage including the mirror 206. Thefluorescence reference plate 5103 is separated by the same opticaldistance from the sensor as that between the sensor and an original onthe platen. The fluorescence reference plate is uniformly coated with afluorescent ink, which exhibits characteristics almost equivalent tothose of the fluorescent ink having the reflection spectrumcharacteristics shown in FIG. 5A, and data obtained using this plate isused for correcting data output from the sensor 210 when the fluorescentlamp 5101 is used.

The signal processing unit 211 electrically processes the read R, G, andB signals to convert them into magenta (M), cyan (C), yellow (Y), andblack (Bk) components, and supplies these components to the printer unit202. One of M, C, Y, and Bk components is supplied to the printer unit202 for each original scanning operation of the image scanner unit 201,and a single print-out operation is completed by a total of fouroriginal scanning operations.

M, C, Y, and Bk frame-sequential image signals sent from the imagescanner unit 201 are supplied to a laser driver 212. The laser driver212 modulation-drives a semiconductor laser 213 in accordance with theimage Signals. A laser beam is scanned on the surface of aphotosensitive drum 217 via a polygonal mirror 214, an f-θ lens 215, anda mirror 216.

A rotary developing unit 218 includes a magenta developer 219, a cyandeveloper 220, a yellow developer 221, and a black developer 222, andthe four developers alternately contact the photosensitive drum todevelop M, C, Y, and Bk electrostatic latent images formed on thephotosensitive drum 217 with corresponding toners.

A paper sheet fed from a paper sheet cassette 224 or 225 is wound arounda transfer drum 223, and the toner image developed on the photosensitivedrum 217 is transferred onto the paper sheet.

In this manner, after the four, i.e., M, C, Y, and Bk color images aresequentially transferred, the paper sheet is exhausted via a fixing unit226.

FIG. 7 shows the arrangement of the CCD sensor 210 used in thisembodiment.

The CCD sensor 210 includes light-receiving element arrays (CCD sensors)210-1, 210-2, and 210-3 for respectively reading R, G, and B wavelengthcomponents.

The three light-receiving element arrays having different opticalcharacteristics are monolithically arranged on a single silicon chip, sothat the R, G, and B sensors are arranged parallel to each other so asto read the same line.

FIG. 6 is an enlarged view of the light-receiving elements. Each sensorhas a main-scan length of 10 μm per pixel. Each sensor has 5,000 pixelsin the main scan direction to be able to read the widthwise direction(297 mm) of an A3-size original at a resolution of 400 dpi. Aninter-line distance between two adjacent ones of the R, G, and B sensorsis 80 μm, and these sensors are separated by 8 lines in correspondencewith the sub-scan resolution of 400 dpi.

Optical filters are respectively formed on the surfaces of the linesensors so as to obtain predetermined R, G, and B spectrumcharacteristics.

The spectrum characteristics of the R, G, and B line sensors of thesensor 210 will be described below with reference to FIG. 12. Theoptical filters are formed on the surfaces of the R, G, and B linesensors to obtain predetermined spectrum characteristics.

FIG. 12 shows the characteristics of conventional R, G, and B filters.As can be seen from FIG. 12, since the conventional R, G, and B filtershave sensitivity with respect to infrared light of 700 nm or higher, aninfrared cut filter shown in FIG. 13 is provided to the lens 209.

FIGS. 1A and 1B are block diagrams showing the flow of image signals inthe image scanner unit 201. The image signals output from the CCD sensor210 are input to an analog signal processing unit 4001, and areconverted into 8-bit digital image signals. Thereafter, these digitalimage signals are input to a shading correction unit 4002.

A decoder 4008 generates CCD driving signals (e.g., shift pulses, resetpulses, and the like) in units of lines by decoding main scan addressesfrom a main scan address counter 419.

A clock generating circuit 430 outputs predetermined signals topredetermined devices of this embodiment.

A VSYNC signal is an image effective period signal in the sub-scandirection, and is sequentially generated in the image reading (scanning)order, i.e., in the order of (M), (C), (Y), and (Bk). A VE signal is animage effective period signal in the main scan direction, and definesthe timing of a main scan start position. A CLK signal is a pixelsynchronization signal, and transfers image data at the timing of theleading edge of 0→1. An HSYNC signal is a timing pulse output insynchronism with a reading operation per line of (M), (C), and (Y).

FIG. 2 is a block diagram of the analog signal processing unit 4001.Since the unit 4001 includes the same R, G, and B processing circuits,FIG. 2 shows a circuit for one color. An image signal output from theCCD sensor 210 is sampled and held by a sample & hold (S/H) unit 4101 soas to stabilize an analog signal waveform. A CPU 417 controls a variableamplifier 4103 and a clamp circuit 4102 via a voltage control circuit4104 so that the image signal can fully utilize the dynamic range of anA/D converter 4105. The A/D converter 4105 converts an analog imagesignal into an 8-bit digital image signal.

The 8-bit digital image signal is subjected to shading correction by aknown shading correction means in the shading correction unit 4002.

When the fluorescent lamp 5101 is used, the CPU stores a fluorescencesignal for one line read from the fluorescence reference plate 5103 incorresponding line memories 4003 in correspondence with the read signalfrom the sensor 210, calculates multiplication coefficients forconverting read data of pixels stored in the line memories into 255levels in units of pixels, and stores these coefficients in coefficientmemories 4006 for one line. When an actual original is read, the CPUreads out the multiplication coefficients corresponding to output pixelsin synchronism with the pixel signals of a line read by the sensor 210,and causes multiplication devices (to be referred to as multipliershereinafter) 4007 to multiply the pixel signals from the sensor 210 withthe multiplication coefficients, thereby achieving shading correction.

Shading correction upon using the halogen lamp 205 is performed in thesame manner as that upon using the fluorescent lamp 5101. That is, aread signal for one line from the standard white plate 5102 is stored inthe line memories, multiplication coefficients for converting pixelvalues of the stored signal into 255 levels are stored in thecoefficient memories, and the read signal is multiplied with themultiplication coefficients in units of pixels from the coefficientmemories by the multipliers.

As shown in FIG. 6, since the light-receiving units (light-receivingelement arrays) 210-1, 210-2, and 210-3 are arranged to be separated bya predetermined distance, spatial shifts in the sub-scan direction amongthese light-receiving units are corrected by delay elements 401 and 402.More specifically, R and G signals obtained by reading an original priorto a B signal in the sub-scan direction are delayed in the sub-scandirection to be synchronized with the B signal. Log converters 403, 404,and 405 comprise look-up table ROMs, and respectively convert luminancesignals into density signals. A known masking and UCR circuit 406 (adetailed description thereof will be omitted) outputs Y, M, C, and Bksignals each having a predetermined bit length (e.g., 8 bits) inaccordance with input three primary color signals every time a readingoperation is performed.

A counter 20101 counts the number of fluorescent pixels from an originalin synchronism with the clocks CLK. In this embodiment, an 8-bit counteris used, and accumulates a maximum of 255 fluorescent pixels.

A detection circuit 4009 discriminates based on 8-bit R, G, and Bsignals whether or not each pixel is a fluorescent pixel. Since afluorescent mark used in this embodiment has reflection spectrumcharacteristics shown in FIG. 5A, the detection circuit determines afluorescent pixel when the value of a G signal is equal to or greaterthan 80H.

A 4-input AND Gate 20102 supplies a binary fluorescence signal outputfrom the detection circuit 4009 as an enable signal of the counter 20101when the main scan effective period signal VE and the sub-scan effectiveperiod signal VSYNC are generated.

The counter 20101 is cleared to "0" in response to a CLR signal from theCPU. In response to this clear signal, a flip-flop (F/F) 20103 is set,and enables an output from the gate 20102.

When a binary signal is input beyond the maximum count value "255" ofthe counter 20101, the counter 20101 generates an RC signal when theoutput from the counter 20101 has reached "255", the F/F 20103 is resetin response to the RC signal, and an enable input of the counter isforcibly set to be "0", thereby holding the counter output to be "255".

The CPU 417 reads the count result of the counter 20101 as a CNT signal.When the count result is equal to or larger than a predetermined value(e.g., equal to or larger than 128 pixels), the CPU detects that acopy-inhibited original is placed on the platen.

A means for acquiring information of only the fluorescent ink of anoriginal will be described below.

As can be seen from FIG. 12, the sensor 210 has no sensitivity in awavelength range of 400 nm or below. Referring to FIG. 5A, since thefluorescent lamp 5101 has a very small light amount in a wavelengthrange of 400 nm or above, when an original without any fluorescent inkis illuminated with light from the fluorescent lamp 5101, the sensor 210detects almost no signals. However, when an original with thefluorescent ink is illuminated with light from the fluorescent lamp5101, the sensor 210 can detect fluorescence of the fluorescent inkwithin its sensitivity range. When the fluorescent lamp has a sufficientlight amount in a light wavelength range which can be detected by thesensor, light in the light wavelength range which can be detected by thesensor becomes noise in data detection of the fluorescent ink. In orderto achieve stable detection in processing for detecting a fluorescentmark, an S/N ratio as high as 2 or more is required. Since the reflectedlight amount from the fluorescent ink with respect to the incident lightamount upon fluorescence of the fluorescent ink is 50% in the worstcase, a fluorescent lamp, whose fluorescent lamp light amount in a rangewherein the sensor has effective sensitivity is at least 1/4 or less ofthe incident light intensity at a wavelength at which the fluorescentink is excited, is used.

When information of the fluorescent ink is acquired by turning on thefluorescent lamp 5101, the halogen lamp 205 is turned off so as toreliably detect information of only the fluorescent ink. Alternatively,the light amount of the halogen lamp 205 is decreased to a level whichdoes not influence the information acquisition to obtain a similareffect, and at the same time, a decrease in temperature of the lamp canbe prevented in this case. Conversely, when image data is acquired byturning on the halogen lamp 205, if the fluorescent lamp 5101 is keptON, since the fluorescent ink emits fluorescence, and image data havinga color tone different from that of an original may be acquired, or anoriginal or the standard white plate may deteriorate, the fluorescentlamp 5101 is turned off to avoid the above-mentioned problems.

Alternatively, the light amount of the fluorescent lamp is decreased toa level which does not influence the image data acquisition to obtain asimilar effect, and at the same time, a decrease in lamp temperature canbe prevented in this case.

The light amount adjustment method of the halogen lamp 205 and thefluorescent lamp 5101, and the control method of the variable amplifiers4103 and the clamp circuits 4102 will be described below with referenceto the flow chart shown in FIGS. 3A and 3B. Since the amount of lightreflected by the fluorescent ink using the fluorescent lamp is verysmall, the gain of the variable amplifier is changed in correspondencewith which of the halogen lamp and the fluorescent lamp is used.

FIG. 4 is a block diagram of light amount control units 4301 and 4302 ofthe halogen lamp 205 and the fluorescent lamp 5101. In the analog signalprocessing unit 4001, in order to fully utilize the dynamic ranges ofthe A/D converters 4105, the gains of the variable amplifiers 4103 areadjusted on the basis of image data obtained upon reading of thestandard white plate 5102, and the control voltages of the clampcircuits 4102 are adjusted by the corresponding voltage control circuits4104 on the basis of image data obtained when no light is radiated onthe sensor 210.

When an adjustment mode is started by an operation unit (not shown), thereflection mirror 206 is moved to a position below the standard whiteplate 5102, and a predetermined gain for the halogen lamp is set in eachvariable amplifier 4103 (step 1). Image data obtained when no light isradiated on the CCD sensor 210 is stored in the line memories (shadingRAMs) 4003. The CPU 417 calculates an average value of the stored imagedata for one line, and controls the voltage control circuits 4104 sothat the average value of the image data for one line becomes closest to08H, thereby adjusting the reference voltages of the clamp circuits 4102(steps 2 and 3). The adjusted control value is stored in a RAM 418connected to the CPU 417 (step 4).

Then, the halogen lamp 205 is turned on, and image data obtained uponreading of the standard white plate 5102 are stored in the line memories4003. The CPU 417 controls the light amount control unit 4301, so thatthe peak value of a G signal falls within a range from D0H to F0H (steps5 and 6; halogen lamp adjustment). The CPU stores the adjusted controlvalue in the RAM 418 connected to the CPU 417 (step 7). Then, thehalogen lamp 205 is turned on to have the light amount adjusted in steps5 and 6, and R, G, and B image data obtained upon reading of thestandard white plate 5102 are stored in the corresponding line memories4003. Then, the voltage control circuits 4104 are controlled, so thatthe peak values of R, G, and B image data fall within a range from E0Hto F8H, thereby adjusting the gains of the variable amplifiers 4103 incorrespondence with R, G, and B colors (steps 8 and 9). The adjustedgains are stored as gain data (to be referred to as H-gain datahereinafter) corresponding to the halogen lamp 205 in the RAM 418connected to the CPU 417. Thereafter, the halogen lamp 205 is turned off(step 10).

In order to adjust the light amount of the fluorescent lamp 5101, thereflection mirror 206 is moved to a position below the fluorescencereference plate 5103, and a predetermined gain for the fluorescent lampis set in each variable amplifier 4103 (step 11). Image data obtainedwhen no light is radiated on the CCD 210 are stored in the line memories4003. The CPU 417 calculates an average value of the stored image datafor one line, and controls the voltage control circuits 4104 so that theaverage value of the image data for one line becomes closest to 08H,thereby adjusting the reference voltages of the clamp circuits 4102(steps 12 and 13). The adjusted control value is stored in the RAM 418connected to the CPU 417 (step 14).

Then, the fluorescent lamp 5101 is turned on, and image data obtainedupon reading of the fluorescence reference plate 5103 are stored in theline memories 4003. The CPU 417 controls the light amount control unit4302, so that the peak value of the G signal falls within a range fromD0H to F0H (steps 15 and 16; fluorescent lamp adjustment), and theadjusted value is stored in the RAM 418 connected to the CPU 417 (step17). Then, the fluorescent lamp 5101 is turned on to have the lightamount adjusted in step 17, and image data obtained upon reading of thefluorescence reference plate 5103 are stored in the shading RAMs 4003.The voltage control circuits 4103 are controlled, so that the peakvalues of R, G, and B image data fall within a range from E0H to F8H,thereby adjusting the gains of the variable amplifiers 4103 in units ofR, G, and B colors (steps 18 and 19). The adjusted gains are stored asgain data (to be referred to as UV-gain data hereinafter) correspondingto the fluorescent lamp 5101 in the RAM 418 connected to the CPU 417.Thereafter, the fluorescent lamp 5101 is turned off (step 20).

In this embodiment, the presence/absence of the fluorescent ink in acopy-inhibited original is detected.

In some copy-inhibited originals such as paper money, a fluorescentmaterial with fluorescent characteristics is mixed in paper fibers ofpaper money like in Canadian dollar bills.

In this embodiment, a fluorescent mark is detected from thin lineinformation such as a fiber having reflection spectrum characteristicsshown in FIG. 5A as an example of such a fiber, thereby detecting acopy-inhibited original. In this embodiment, the number of pixels offluorescent information included in an original is counted, and when thecount value is equal to or larger than a predetermined value, it isdetermined that an original is a copy-inhibited original.

The actual operation will be described below with reference to the flowchart shown in FIG. 8.

When an operator sets an original on the platen 203, and starts acopying operation using an operation unit (not shown), the CPU 417controls a motor (not shown) to move the reflection mirror 206 to aposition below the fluorescence reference plate 5103 (step 1). Then, theUV-gain data are set in the corresponding variable amplifiers 4103 viathe voltage control circuits 4104 of the analog signal processing unit4001 (step 2). The fluorescent lamp 5101 is turned on based on thecontrol value set in the fluorescent lamp adjustment to illuminate thefluorescence reference plate 5103. In the shading correction unit 4002,shading data corresponding to the fluorescent lamp 5101 are stored inthe corresponding line memories 4003, and known shading correction isexecuted (step 3). In step 4, the CPU 417 clears the counter 20101 andthe F/F 20103. The original reading operation is performed (step 5;pre-scan), and the detection circuit 4009 counts the number offluorescent pixels on the original 204 (step 6). It is then checked ifthe number of fluorescent pixels is equal to or larger than apredetermined value (in this case, 128) (step 7).

If it is determined in step 7 that the number of fluorescent pixels isequal to or larger than the predetermined value, it is determined thatthe original 204 is a copy-inhibited original, and the copying operationends.

If it is determined in step 7 that the number of fluorescent pixels issmaller than the predetermined value, i.e., if it is determined that theoriginal 204 is not a copy-inhibited original, the reflection mirror 206is moved to a position below the standard white plate 5102 (step 8), andthe H-gain data are set in the corresponding variable amplifiers 4103(step 9). The halogen lamp 205 is turned on based on the control valueset in the halogen lamp adjustment to illuminate the standard whiteplate 5102. In the shading correction unit, shading data correspondingto the halogen lamp 205 are stored again in the line memories 4003, andknown shading correction is executed (step 10). Then, a total of fournormal reading operations are performed in correspondence with M, C, Y,and Bk colors (step 11), and the printer unit 202 executes an imageformation operation (step 12), thus ending the copying operation.

All the above-mentioned control operations are executed by the CPU 417.When light emitted from the halogen lamp 205 includes a wavelengthcomponent which excites the fluorescent ink, a filter for cutting thewavelength component which excites the fluorescent ink may be arrangedbetween the halogen lamp 205 and the original 204.

Second Embodiment

FIG. 10 is a schematic sectional view showing a copying apparatusaccording to the second embodiment, and FIG. 14 is a schematic sectionalview showing an original illumination unit of the copying apparatus ofthe second embodiment. In the second embodiment, the number ofillumination light sources is decreased from two to one, and the lightwavelength range upon illumination of an original is changed byswitching filters inserted in the optical path between the light sourceand an original in addition to the features of the first embodiment.

Referring to FIG. 14, a fluorescent lamp 5205 exhibits spectrumcharacteristics shown in FIG. 15A, and its illumination direction islimited by a light-shielding cover 5206. A visible light cut filter 5203exhibits characteristics shown in FIG. 15B. An ultraviolet cut filter5204 exhibits characteristics shown in FIG. 15C. These two filters aremounted on a base 5201 having a glass plate portion, and the base 5201is moved by a solenoid 5202 in a direction parallel to the platen 203.FIG. 14 shows an arrangement when the solenoid 5202 is located at aposition "D", and ultraviolet rays are to be radiated onto an original.In this arrangement, radiation light from the fluorescent lamp 5205 isfiltered through the visible light cut filter 5203, and only ultravioletrays are radiated on an original. Light reflected by the original isfiltered through the ultraviolet cut filter 5204, and light excludingultraviolet rays is guided toward the sensor via the reflection mirror206. When normal full-color data is to be read, the solenoid 5202 movesto the "U" side, radiation light from the fluorescent lamp 5205 isfiltered through the ultraviolet cut filter 5204, and light excludingvisible light is radiated onto an original. Light reflected by theoriginal is guided to the sensor via the reflection mirror 206. In thesecond embodiment, since a common light source is used, data correctionof the sensor 210 upon illumination of an original is achieved bymultiplying correction means of the sensor 210 obtained using thestandard white plate 5102 upon illumination of an original with visiblelight with coefficients obtained based on experimental data. As shown inFIG. 10, the filters used in this embodiment have a film shape, and donot influence the optical path length of an original reading system.

Third Embodiment

FIG. 16 is a schematic sectional view of an original illumination unitof an image forming apparatus according to the third embodiment. In thethird embodiment, the excitation wavelength of a fluorescent material asan object to be detected is present within a visible light wavelengthrange in addition to the features of the second embodiment.

Referring to FIG. 16, a halogen lamp 5209 exhibits spectrumcharacteristics shown in FIG. 17A, and its focusing and illuminationdirections are limited by a reflector 5210. A filter 5207 allows onlylight of the excitation wavelength of the fluorescent material to passtherethrough, and exhibits characteristics shown in FIG. 17B. Thisfilter is mounted on the base 5201, and the base 5201 is moved by thesolenoid 5202 in a direction parallel to the platen 203, as in thesecond embodiment. FIG. 16 shows an arrangement in which the solenoid5202 is located at a position "D", and the fluorescent material is to bedetected. At this time, radiation light from the halogen lamp 5209 isfiltered through the filter 5207, and only light of a specificwavelength is radiated onto an original. Light reflected by the originalis guided to the sensor via the reflection mirror 206. FIG. 17C showsthe spectrum light amount of reflected light of the fluorescent materialused in the third embodiment with respect to the spectrum light amountof the specific wavelength illumination means. In the third embodiment,a CCD which exhibits the spectrum sensitivity shown in FIG. 12 as in thefirst embodiment is used. The fluorescent material is detected asfollows. That is, in original scanning, pixel data is binarized based onwhether R pixel data from the sensor is equal to or larger than A0H, andwhen the number of pixels equal to or larger than A0H obtained by addingthe binary pixel data exceeds 255, it is determined that an original isa copy-inhibited original, thus ending the copying operation as in thefirst embodiment.

If it is determined that an original is not a copy-inhibited original,the solenoid 5202 moves to the "U" side, and radiation light from thehalogen lamp 5209 is radiated onto an original without going through thefilter. Light reflected by the original is guided to the sensor via thereflection mirror 206. Note that the filter used in this embodiment hasa film shape, and does not influence the optical path length of anoriginal reading system. When light emitted from the halogen lamp 5209is radiated onto the fluorescent material without going through thefilter 5207, since the amount of the excited visible fluorescence isconsiderably smaller than that of visible light reflected by theoriginal, no problem of a shift in color tone of full-color image datais not posed.

Fourth Embodiment

FIGS. 18 and 19 are schematic sectional views of an originalillumination unit of an image forming apparatus according to the fourthembodiment. In the fourth embodiment, the excitation wavelength of afluorescent material to be detected is present within an infraredwavelength range in addition to the features of the second embodiment.

The fourth embodiment will be described below as in the second and thirdembodiments. A fluorescent material as an object to be detected in thefourth embodiment is based on multi-stage energy transmission, and morespecifically, is a fluorescent compound of BaY₁.34 Yb₀.60 Er₀.06 F₈.FIG. 20A shows the light-emission spectrum of fluorescence excited lightof a fluorescent material of this embodiment with respect to incidentlight. A halogen lamp 5209 in FIG. 18 has spectrum characteristics shownin FIG. 17A, and its focusing and illumination directions are limited bya reflector 5210. FIG. 20B shows spectrum characteristics of a filter5215 which allows only light of the excitation wavelength of thefluorescent material to pass therethrough. An infrared cut filter 5216limits light of a wavelength equal to or higher than 750 nm, and FIG.20C shows its characteristics. A glass 5217 has the same opticaldistance as those of the two filters. These components 5215 to 527 aremounted on the base 5201 as in the second embodiment, and the base 5201is moved by the solenoid 5202 in a direction parallel to the platen 203.FIG. 18 shows an arrangement upon detection of the fluorescent material.At this time, radiation light from the halogen lamp 5209 is filteredthrough the filter 5215, and only light of a specific wavelength, i.e.,having 950 nm as a peak wavelength, is radiated onto an original. Lightreflected by the original is filtered through the infrared cut filter5216, and light of only wavelength components equal to or lower than 750nm is guided to the sensor via the reflection mirror 206. In the fourthembodiment, a CCD which exhibits the spectrum sensitivity shown in FIG.12 as in the first embodiment is used. The fluorescent material to bedetected is detected as follows. That is, as can be seen from FIG. 20A,the spectrum characteristics of fluorescence have a peak in,particularly, a G signal of the spectrum sensitivity of the CCD. Thus,in original scanning, pixel data is binarized based on whether G pixeldata from the sensor is equal to or larger than A0H, and when the numberof pixels equal to or larger than 80H obtained by adding the binarypixel data exceeds 255, it is determined that an original is acopy-inhibited original, thus ending the copying operation as in thefirst embodiment.

If it is determined that an original is not a copy-inhibited original,the solenoid 5202 operates to move the base 5201 to a position shown inFIG. 19. Radiation light from the halogen lamp 5209 is radiated onto anoriginal via the infrared cut filter 5216. In this case, since anoriginal is illuminated with light which has almost no light wavelengthcomponents which can excite the fluorescent material, precise image dataof an original will not be impaired by fluorescence. Light reflected byan original is transmitted through the glass 5217, and is guided to thesensor via the reflection mirror 206.

Fifth Embodiment

FIG. 11 is a schematic sectional view of an original illumination unitof an image forming apparatus according to the fifth embodiment. In thefifth embodiment, the arrangement of the original illumination unit isdifferent from that in the first embodiment. Referring to FIG. 11, afluorescent lamp 5211 emits light (ultraviolet rays) in ashort-wavelength range, which can efficiently excite a normalfluorescent ink. A planar heat generating member 5212 controls thetemperature of the fluorescent lamp 5211 to be constant together with atemperature sensor and a temperature control circuit (neither areshown). A halogen lamp 5218 emits visible light, and outputs almost noultraviolet rays. Focusing reflection plates 5213 and 5214 are arrangedfor efficiently radiating light emitted from the halogen lamp onto anoriginal. In particular, the reflection plate 5213 comprises a dichroicfilter, which allows light of a wavelength lower than 400 nm to passtherethrough, and reflects light of wavelength equal to or higher than400 nm. In the fifth embodiment, the halogen lamp can be turned on at alow voltage, and a compact original illumination unit can be achievedeven though the fluorescent lamp is arranged.

Sixth Embodiment

FIG. 21 is a schematic sectional view of an image forming apparatusaccording to the sixth embodiment. FIG. 22 is a partial sectional viewof an image scanner unit of the image forming apparatus of the sixthembodiment. FIG. 22 shows a state wherein an original illumination unitis located at a home position.

A standard white plate 5222 is used for correcting data read by thesensor 210 when the halogen lamp 205 is used. A fluorescence referenceplate 5223 is uniformly coated with a fluorescent ink which exhibitsalmost equivalent characteristics to those of the fluorescent ink of thefirst embodiment as an object to be detected, and is used for correctingoutput data from the sensor 210 when the fluorescent lamp 5101 is used.

When the halogen lamp 205 is used, correction is executed in thearrangement of the original illumination unit shown in FIG. 22. Also,when the fluorescent lamp 5101 is used, correction is executed bydriving a solenoid 5224 to move a glass member 5221, on which the tworeference plates are mounted, and which has the same thickness as thatof the platen, so that the fluorescence reference plate 5223 is locatedat the position of the standard white plate 5222. When one correctionmeans is executed, a light source associated with the other correctionmeans is turned off so as not to influence the correction means beingexecuted. Furthermore, a light-shielding member 5225 is used forpreventing the standard white plate 5222 from deteriorating by lightemitted from the fluorescent lamp 5101. Note that a common illuminationlight source may be used by switching filters as in the secondembodiment.

Seventh Embodiment

FIG. 23 is a partial sectional view of an image scanner unit of an imageforming apparatus according to the seventh embodiment. FIG. 23 shows astate wherein an original illumination unit is located at the homeposition.

In the seventh embodiment, in order to prevent deterioration of thestandard white plate, a thin-film ultraviolet cut filter 5225 whichexhibits characteristics shown in FIG. 15C used in the second embodimentis inserted between the glass member 5221 and the standard white plate5223 in place of the light-shielding member unlike in the sixthembodiment.

As processing for discriminating that an original image is acopy-inhibited original, in the above description, the copying operationis stopped, a copy is output with a copy-inhibited region painted inblack, a copy is output after a fluorescent mark printed fordiscriminating a copy-inhibited original is visualized thereon, or thelike. In addition, any other methods of stopping a normal copyingoperation may be adopted. For example, the entire output image, or oneor a plurality of portions of an output image may be painted in white,black, or a specific color, or may be output in a specific pattern, awarning tone may be generated or may be supplied via, e.g., a modem, anoriginal image may be inhibited from being removed, the functions of theentire apparatus are stopped, and so on.

As for the method of acquiring information of a fluorescent ink usingthe two systems of original illumination means, the two light sourcesmay be moved to exchange their positions with each other, or an originalillumination focusing reflection plate may be moved to switch theillumination means.

Also, in an original illumination system as a combination of a singlelight source and an optical filter, the light source may be movedrelative to the fixed filter. The filter is not limited to atwo-dimensional filter, but may have a curved shape, or a reflectorhaving characteristics of a filter may be moved.

In the above embodiments, the halogen lamp or the fluorescent lamp hasbeen exemplified. However, the present invention is not limited to theseas long as a light source can emit light in a visible wavelength range.

In the above embodiments, the standard white plate and the fluorescencereference plate are separately prepared. However, the sensor outputs forboth visible light and ultraviolet fluorescence may be corrected using asingle reference plate by using an ultraviolet fluorescent materialwhich exhibits characteristics of white color with respect to visiblelight.

As the single reference plate, a plate obtained by coating anultraviolet fluorescent material, which exhibits characteristics oftransparency with respect to visible light, on a reference plate whichis white under visible light.

Also, a driver common to the fluorescent lamp and the visible light lampmay be used to alternately control these lamps.

Since the amount of reflected light obtained by exciting the fluorescentink is very small, it cannot often be coped with by only changing thegains of the variable amplifiers. In this case, the accumulation time ofthe CCD may be changed in correspondence with which one of the halogenlamp and the fluorescent lamp is used.

In this embodiment, only the full-color reading apparatus has beendescribed. However, the present invention can be applied to a digitalmonochrome copying machine using one or a plurality of lines of CCDs.

As described above, according to each of the embodiments of the presentinvention, since a fluorescent ink is detected from an original, acopy-inhibited original can be reliably detected.

Since the apparatus of each of the above embodiments has originalillumination means having different light wavelength ranges, whichinclude an original illumination means for exciting a fluorescent ink,information of only a fluorescent material can be read.

Of a plurality of original illumination means, when one light source isturned on to read image data, the other light source is turned off orits power is decreased, thus achieving precise reading.

In order to read fluorescence information, the fluorescence referenceplate, which exhibits fluorescent characteristics, is arranged, and theoutputs from the sensor are corrected based on signals obtained byreading the reference plate, thus allowing precise reading offluorescence information.

Since a plurality of reference plates for a plurality of light sourcesare arranged to be separated from each other, deterioration of thereference plates can be prevented.

Since the fluorescent characteristics of the fluorescence referenceplate are set to be equivalent to those of a fluorescent ink printed onan original, fluorescence information can be read more precisely.

Since filters for changing the wavelength ranges of light forilluminating an original from a light source are switched, a singlelight source can achieve original illumination operations which exhibitdifferent spectrum characteristics.

Since information which cannot be identified by visible light isrecorded as visible information, a normal copying operation of acopy-inhibited original can be prevented.

As described above, according to the present invention, thecharacteristics of an original can be reliably detected with a simplearrangement.

Eighth Embodiment

FIG. 25 is a schematic sectional view of an apparatus according to theeighth embodiment.

The same reference numerals in FIG. 25 denote the same parts as in FIG.9, and a detailed description thereof will be omitted.

FIG. 27 shows the outer appearance of a filter frame 1610 (shown in FIG.25) arranged between a mirror 208 and a lens 209. The filter frame 1610comprises an infrared cut filter 1611 and a visible light cut filter1612. FIG. 13 shows the spectrum characteristics of the infrared cutfilter 1611. Of the spectrum characteristics of a halogen lamp 205 shownin FIG. 26, infrared rays of wavelengths equal to or higher than about700 nm are cut by the infrared cut filter 1611. FIG. 28 shows thespectrum characteristics of the visible light cut filter 1612. Of thespectrum characteristics of the halogen lamp 205 shown in FIG. 26,visible light components of wavelengths equal to or lower than about 750nm are cut by the visible light cut filter 1612.

The filter frame 1610 is moved by a drive system 1616 coupled to a hole1615 in accordance with an original reading sequence, so that one of theinfrared cut filter 1611 and the visible light cut filter 1612 islocated in front of the lens 209. A CCD 210 comprises three line pixelarrays, i.e., a pixel array (to be referred to as an R pixel array)210-1 deposited with an R filter, a pixel array (to be referred to as aG pixel array) 210-2 deposited with a G filter, and a pixel array (to bereferred to as a B pixel array) 210-3 deposited with a B filter. FIG. 12shows the spectrum characteristics of the filters deposited on the pixelarrays. Since the pixel arrays are arranged to be separated by apredetermined interval, line buffers are prepared at the output side ofthese pixel arrays, and are controlled, so that the read signals of thesame line from the three lines are not simultaneously supplied to asignal processing unit 211.

A pattern recognition sequence will be described in turn below. In thisembodiment, a copy-inhibited internal original will be exemplified as anexample of an original to be prevented from being forged. However, thepresent invention is not limited to this, but may be applied to papermoney such as bank notes of various countries, securities, and the like.

Original

FIG. 29A shows an internal original (to be simply referred to as anoriginal hereinafter) 1630 on which a pre-registered pattern 1631 isprinted using an infrared fluorescent paint. In addition to the pattern1631, characters and an image 1632 are printed on the original 1630using a normal ink. Fluorescence radiated from the infrared fluorescentpaint to be printed is infrared rays of wavelengths equal to or higherthan 700 nm, and is sensed to be transparent by human eyes, which havesensitivity in a range from 400 to 700 nm. Therefore, it is verydifficult for human eyes to recognize this paint. This infraredfluorescent paint has a feature of emitting fluorescence of a specificwavelength upon radiation of excitation light having a certainwavelength range. FIG. 24 shows the light-emission characteristics offluorescence. A curve 1601 shown in FIG. 24 represents the lightabsorptivity of the infrared fluorescent paint as a function of thewavelength. When this fluorescent agent receives light includinginfrared rays (the spectrum distribution of the light is expressed by acurve 1602 in FIG. 24; the light-emission intensity is plotted along theordinate), it absorbs light in a wavelength range according to thecharacteristic curve 1601, and emits fluorescence whose spectrumdistribution is expressed by a curve 1603 (the light-emission intensityis plotted along the ordinate). As a General feature of the fluorescentagent, when the agent absorbs excitation light, energy of radiationlight is reduced by energy transition of molecules in the fluorescentagent. The radiation light is emitted as fluorescence at a wavelengthhigher than the excitation light since its energy is reduced. In FIG.24, the peak wavelength of the excitation light is shifted by about 100nm from that of the fluorescence.

The spectrum components 1603 of only the fluorescence can be extractedby cutting the wavelength components of the excitation light sourceusing the visible light cut filter 1612. The extracted spectrumcomponents are read by the R pixel array 210-1 of the CCD 210. Thisprocessing will be described in detail later.

Pre-scan

An image scanner unit 201 performs a pre-scan operation aspre-processing of a copying operation of the original 1630. The pre-scanoperation will be described below.

The lamp 205 radiates light onto a white shading plate 1640 adhered to aportion of a platen 203, as shown in FIG. 30. A reflected image from thewhite shading plate 1640 is focused on the CCD 210 via the mirrors 206,207, and 208, the filter frame 1610, and the lens 209 shown in FIG. 25.At this time, the filter frame 1610 is moved by a drive system (notshown), so that the infrared cut filter 1611 is located in front of thelens 209. The image of the white shading plate 1640 read by the CCD 210is subjected to signal processing in the signal processing unit 211.Correction data for illumination nonuniformity of the lamp 205, andsensitivity nonuniformity in units of pixels of the R, G, and B pixelarrays 210-1, 210-2, and 210-3 on the CCD 210 are generated, and arestored in a memory 211-2. Thereafter, the lamp 205 is mechanically movedby a drive system (not shown) at a speed v in the direction of an arrowm in FIG. 30, thereby scanning the entire surface of the original. Atthis time, the maximum and minimum values of original densities aresampled from the image of the original 1630 read by the CCD 210, and aprint density setting value in the copying operation is calculated.

Upon completion of scanning of the final line of the original 1630, thelamp 205 then radiates light onto an infrared shading plate 1641 adheredto another portion of the platen 203, as shown in FIG. 31. In thisembodiment, the infrared shading plate 1641 is adhered to the leftmostend portion of the platen 203, while the white shading plate 1640 isadhered to the rightmost end portion of the platen 203.

The infrared shading plate 1641 is uniformly coated with theabove-mentioned infrared fluorescent paint, and emits fluorescence uponradiation of infrared rays included in light emitted from the lamp 205,as has been described above with reference to FIG. 24. At this time, thefilter frame 1610 is driven by the drive system 1616, so that thevisible light cut filter 1612 is located in front of the lens 209. Thus,only fluorescence is incident on the CCD 210. In this case, since lightincident on the G and B pixel arrays 210-2 and 210-3 is cut over theentire wavelength range due to a synergistic effect of the filtersdeposited on these pixel arrays, and the visible light cut filter, onlythe R pixel array 210-1 whose transmission spectrum range extends up toan infrared range (see the curve Red in FIG. 12) can actually detect asignal. As described above, the infrared shading plate 1641 is arrangedfor correcting illumination nonuniformity of infrared rays included inlight emitted from the lamp 205, and sensitivity nonuniformity of theCCD 210 with respect to infrared rays. With this arrangement, ahigh-precision infrared reading system can be realized, and shadingcorrection processing can be executed not only for a visible light rangebut also for an infrared range. The energy of the infrared components ofthe lamp 205 is as low as a fraction of energy of the visible lightcomponents, and an image reading operation cannot often besatisfactorily attained if electrical setting of a scanner unit uponreading of the white shading plate or an original is left unchanged.Thus, in this embodiment, the infrared shading plate is arranged, asdescribed above, and a drive signal of the CCD 210 is properlycontrolled to obtain an image signal of a sufficient level. Such controlwill be exemplified below.

FIG. 32 is a timing chart of the drive signal of the CCD 210 uponreading of the white shading plate or an original. Signals φ1 and φ2 aretransfer clocks of an internal shift register of the CCD 210, and aperiod T of the signals φ1 and φ2 is T=t1. Data for one pixel is outputin one period of the signals φ1 and φ2. If the number of pixels of eachof the R, G, and B pixel arrays of the CCD 210 is 5,000, a time requiredfor outputting all the 5,000 pixels, i.e., 5,000×t1 corresponds to anaccumulation time Tint. As is apparent from FIG. 32, the accumulationtime Tint also corresponds to a time of one period of a main scansynchronization signal φTG of the CCD 210.

In contrast to this, FIG. 33 is a timing chart of the drive signal ofthe CCD 210 upon reading of the infrared shading plate or upon executionof pattern detection (to be described later). Signals φ1' and φ2' aretransfer clocks of an internal shift register of the CCD 210. A periodT' of the signals φ1' and φ2' is T'=t2=2×t1, and is twice as long as theperiod of the signals φ1 and φ2. Therefore, an accumulation time Tint'at this time becomes twice as long as the time Tint, and an image dataoutput from the CCD 210 based on infrared rays is almost doubled, thusassuring a wide dynamic range.

If an output signal of a sufficient level cannot be obtained by thismethod, light amount adjustment control of the lamp 205 is alsoexecuted. More specifically, when the infrared shading plate is read, orpattern detection is executed, the light amount of the lamp 205 iscontrolled to increase up to a level at which a signal sufficient forreading can be obtained, thus obtaining an output signal of a levelsufficient for reading and detection.

Furthermore, the gain of an analog amplifier unit for amplifying theoutput signal from the CCD may be switched. For example, in an infraredreading system, the gain is increased to increase the amplitude of asignal, thus assuring a sufficient dynamic range.

With the above-mentioned method, an image of the infrared shading plate1641 is subjected to signal processing of infrared rays in the signalprocessing unit 211, and correction data for illumination nonuniformityof infrared components of light emitted from the lamp 205, andsensitivity nonuniformity of the R pixel array 210-1 on the CCD 210 withrespect to infrared rays are generated. Thereafter, the lamp 205 ismechanically moved by a drive system (not shown) at the speed v in adirection of an arrow n (FIG. 31), thus starting an operation forreturning the lamp 205 to the reading start position, i.e., the homeposition.

Pattern Detection

After the above-mentioned infrared shading correction processing iscompleted, the lamp 205 is moved in the direction of the arrow n, and isreturned to the home position. At this time, the lamp 205 scans theoriginal 1630 while it is kept ON, thereby detecting whether or not thepattern 1631 is printed on the original 1630. In this case, the filterframe 1610 is held in a state after the infrared shading correctionprocessing. More specifically, the frame 1610 is driven, so that thevisible light cut filter 1612 is located in front of the lens 209. Animage is read by the R pixel array 210-1 for the above-mentioned reason.At this time, if no pattern 1631 expressed by the fluorescent agent ispresent on the original 1630, an image signal read by the CCD 210 has alevel almost equal to the black level. However, if the pattern 1631 ispresent on the original 1630, only this portion emits fluorescence, andthe pattern is detected by the R pixel array 210-1 of the CCD 210. FIG.29B shows a state wherein the original 1630 including the pattern 1631is read. Referring to FIG. 29B, the R pixel array 210-1 generates awhite-level output in correspondence with the portion of the pattern1631, while it generates a black-level output in correspondence with theremaining region 1633. The image shown in FIG. 29B, which is read by theCCD 210 is temporarily stored in a memory 211-3, and a discriminationcircuit 211-5 checks if the stored image is similar to a patternpre-registered in a memory such as a ROM 211-4. The discriminationmethod of these patterns is achieved by adopting a method known aspattern matching. Since the original 1630 may be placed on the platen203 at every possible angle, patterns for various angles are preferablyregistered as long as the ROM capacity allows. Alternatively, in thecase of similarity discrimination, one pattern is stored in the ROM, andthe arrangement of the pattern stored in the ROM may be changed toattain various pattern discrimination operations. Furthermore, whendiscrimination is realized by the fuzzy theory, high-speed,high-precision discrimination can be realized.

The above-mentioned infrared fluorescent paint used for printing apattern is assumed to have characteristics that both the excitationwavelength and the fluorescent wavelength are present in the infraredwavelength range, as shown in FIG. 24. However, according to the presentinvention, the fluorescent paint for printing a pattern is not limitedto the paint having the above-mentioned feature. For example, as shownin FIG. 37, a pattern may be printed using an ultraviolet paint, whichabsorbs light in a wavelength range according to a characteristic curve1701 expressing the light absorptivity as a function of the wavelength,and emits fluorescence whose spectrum distribution is expressed by acurve 1703 in FIG. 37. At this time, the spectrum distribution of thelamp 205 has characteristics expressed by a curve 1702, and at the sametime, the visible light cut filter shown in FIG. 27 must havecharacteristics for cutting ultraviolet rays. Also, as shown in FIG. 38,a pattern may be printed using a visible light paint, which absorbslight in a wavelength range according to a curve 1711 expressing thelight absorptivity as a function of the wavelength, and which emitsfluorescence whose spectrum distribution is expressed by a curve 1713.At this time, the lamp 205 can have a spectrum distribution expressed bythe characteristic curve 1602 described above with reference to FIG. 24,and the visible light cut filter 1612 shown in FIG. 27 can havecharacteristics shown in FIG. 26. In this case, since the visible lightpaint for printing a pattern is recognized by human eyes, such a paintis preferably applied to an original which has no difficulty even when aprinted position of the pattern is recognized.

Original Copying

Upon completion of the pattern detection sequence, when the pattern isrecognized, a control circuit 250 in the copying machine (FIG. 25)temporarily stops a copying operation. Thereafter, the control circuit250 asks an operator for an identification number. When noidentification number is input within a predetermined period of time,the original copying operation is stopped. When an identification numberis input, the filter frame 1610 is driven by the drive system 1616, sothat the infrared cut filter 1611 is re-arranged in front of the lens609, and an original image is read while cutting unnecessary infraredrays. At this time, read image data is subjected to shading correctionon the basis of shading correction data obtained by reading the whiteshading plate, and the corrected image data is subjected to imageprocessing such as edge emphasis, masking processing, and the like inthe signal processing unit 211. The processed image data is supplied tothe printer unit 202, and the original image is copied.

Ninth Embodiment

In the above description, only one lamp is used as an illumination lightsource. However, as the lamp 205, a lamp having large energy of visiblelight components for reading an original is assumed, and infrared raysare secondary output components. Therefore, as shown in FIG. 34, as alight source upon reading of the infrared shading plate or uponexecution of pattern detection, it is effective to add a lamp 1670 tothe above embodiment of the present invention. More specifically, asshown in FIG. 35, the lamp 1670 has characteristics that it has smallenergy of visible light components but large energy of infraredcomponents, and has no fluorescent spectrum components generated by theinfrared fluorescent paint. Since the fluorescent agent hascharacteristics that the energy of fluorescence increases as the energyof excitation light is larger, an original is read by turning on thelamp 205 and turning off the lamp 1670 in an original reading mode, andis read by turning off the lamp 205 and turning on the lamp 1670 in apattern detection mode, thus obtaining CCD outputs suitable for thesereading modes.

Tenth Embodiment

In the above embodiment, the white and infrared shading plates arearranged at the two end portions of the platen, as shown in FIG. 30, 31,or 34. Alternatively, as shown in FIG. 36, two shading plates 1640 and1641 may be integrally arranged. With this arrangement, since alimitation on the order of the pre-scan operation and the patterndetection described above can be removed, a copying operation can beperformed in a convenient order depending on a mode for executing acopying operation. Also, a merit of a decrease in the number of partscan also be obtained.

Eleventh Embodiment

In the above embodiment, after shading correction using the whiteshading plate is performed, shading correction for the infraredwavelength range using the infrared shading plate is performed. When thepositions of the two shading plates are replaced with each other,shading correction using the white shading plate may be performed aftershading correction for the infrared wavelength range using the infraredshading plate is performed. With this control, since a time requiredfrom the copy start up to pattern detection can be shortened, even whenan original printed with a pattern and an original without a pattern aremixed, the total copying processing time can be shortened.

Twelefth Embodiment

In the above embodiment, only one reading sensor is prepared, and iscommonly used for both pattern detection and original reading. However,another sensor may be prepared for pattern detection. In patterndetection, a pattern need only be discriminated. For this reason, sincethe resolution is not particularly limited, and an inexpensiveblack-and-white sensor can be used, if a sensor having a wide openingwindow is selected to assure a required output dynamic range, patterndetection precision in a pattern detection mode can be improved.

Thirteenth Embodiment

In the above embodiment, when a pattern is detected on an original, anidentification number is input, and only when a coincidence of thenumber is detected, original copying processing is allowed.Alternatively, some patterns may be registered in advance, and copyingpermission levels may be set in correspondence with the patterns. Forexample, the following application is available. That is, when a pattern"AAA" is detected, a copying operation is inhibited without anyexceptions; when a pattern "BBB" is detected, a copying operation isallowed to only a person who can input an identification number.

When a pattern is detected on an original, an add-on pattern, which canbe recognized by man may be added to a portion corresponding to thepattern, or when a pattern is detected on an original even partially, anadd-on pattern may be added to the entire original. In this case, acopying operation of an original image need only be prevented bymodifying an original image. When a specific image is detected, acopying operation may be stopped unconditionally.

When a pattern printed on, e.g., a specific original using a fluorescentpaint is recognized, the spectrum distribution of fluorescence emittedfrom the paint falls within an infrared or ultraviolet non-visible lightrange. However, in shading correction processing executed by a normalimage reading system, shading correction data is generated on the basisof data obtained by reading a standard white plate, and shadingcorrection processing is executed based on the generated data. For thisreason, sufficient correction cannot be expected upon reading of anon-visible light range. Therefore, image reading precision anddiscrimination of a specific image cannot have a satisfactory level.

However, in the above embodiment, in an apparatus in which apredetermined pattern is printed on a copy-inhibited original using aninfrared fluorescent paint, and a copying machine comprises infraredfluorescence reading means, shading correction processing is performedbased on data obtained by illuminating a first shading correction platesuitable for a reading system using infrared light in a patternrecognition sequence, and shading correction processing is performedbased on data obtained by illuminating a second shading correction platesuitable for a reading system using visible light in a reading sequence.Therefore, the shading correction can be satisfactorily performed inboth the recognition sequence and the reading sequence.

Since these sequences can use a common reading sensor and illuminationlight source, the apparatus can be simplified, and cost can be reduced.

According to the present invention, a specific image can be stably andautomatically discriminated with high precision.

In the above embodiment, the copying apparatus has been exemplified.However, the present invention is not limited to the copying apparatus,but may be applied to various image input apparatuses such as a scanneras a method of discriminating a specific original.

What is claimed is:
 1. An image reading apparatus which comprisesillumination means for radiating both light including a visiblecomponent and light including a non-visible component, and detectionmeans for detecting light obtained from an image in accordance with thelight radiated from said illumination means, further comprising:firstfilter means which can be switched in accordance with whether thevisible or non-visible component is radiated from said illuminationmeans onto the image; control means for controlling a switchingoperation of said filter means; and second filter means for changing alight component detected by said detection means.
 2. An apparatusaccording to claim 1, wherein said first filter means cuts a lightcomponent other than a light component radiated onto the image.
 3. Animage reading apparatus which comprises illumination means for radiatingboth light including a visible component and light including anon-visible component, and detection means for detecting light obtainedfrom an image in accordance with the light radiated from saidillumination means, further comprising:filter means which can beswitched in accordance with whether the visible or non-visible componentis radiated from said illumination means onto the image; control meansfor controlling a switching operation of said filter means; andcorrection means, having a reference plate, for detecting data obtainedupon radiation of light onto said reference plate by said illuminationmeans, and for correcting one or both of said illumination means andsaid detection means.
 4. An apparatus according to claim 3, wherein saidfilter means cuts a light component other than a light componentradiated onto the predetermined image.
 5. An apparatus according toclaim 3, wherein correction of said illumination means is light amountcorrection of a lamp.
 6. An apparatus according to claim 3, whereincorrection of said detection means is output correction of a sensor. 7.An apparatus according to claim 3, wherein a plurality of said referenceplates are arranged in correspondence with the visible and non-visiblecomponents.
 8. An apparatus according to claim 3, wherein said referenceplate is commonly used for the visible and non-visible components.
 9. Anapparatus according to claim 3, wherein a plurality of said referenceplates are separately arranged in correspondence with the visible andnon-visible components, and said apparatus further compriseslight-shielding means for shielding radiation of light on a referenceplate other than a reference plate corresponding to a light component tobe radiated via said filter means.
 10. An apparatus according to claim3, wherein the light detected by said detection means is visible.
 11. Anapparatus according to claim 3, wherein the light detected by saiddetection means is non-visible.
 12. A copying apparatus which comprisesillumination means for radiating both light including a visiblecomponent and light including a non-visible component, detection meansfor detecting light obtained from an image in accordance with the lightradiated from said illumination means, and discrimination means fordiscriminating based on a detection result of said detection meanswhether or not a specific image is present, further comprising:firstfilter means which can be switched in accordance with whether thevisible or non-visible component is radiated from said illuminationmeans onto the image; control means for controlling a switchingoperation of said filter means; and second filter means for changing alight component detected by said detection means.
 13. An apparatusaccording to claim 12, further comprising input means for inputting datafor canceling said discrimination means.
 14. An apparatus according toclaim 12, wherein said first filter means cuts a light component otherthan a light component radiated onto the image.
 15. A copying apparatuswhich comprises illumination means for radiating both light including avisible component and light including a non-visible component, detectionmeans for detecting light obtained from an image in accordance with thelight radiated from said illumination means, and discrimination meansfor discriminating based on a detection result of said detection meanswhether or not a specific image is present, further comprising:filtermeans which can be switched in accordance with whether the visible ornon-visible component is radiated from said illumination means onto theimage; control means for controlling a switching operation of saidfilter means; and correction means, having a reference plate, fordetecting data obtained upon radiation of light onto said referenceplate by said illumination means, and for correcting one or both of saidillumination means and said detection means.
 16. An apparatus accordingto claim 15, wherein said filter means cuts a light component other thana light component radiated onto the image.
 17. An apparatus according toclaim 15, wherein correction of said illumination means is light amountcorrection of a lamp.
 18. An apparatus according to claim 15, whereincorrection of said detection means is output correction of a sensor. 19.An apparatus according to claim 15, wherein a plurality of saidreference plates are arranged in correspondence with the visible andnon-visible components.
 20. An apparatus according to claim 15, whereinsaid reference plate is commonly used for the visible and non-visiblecomponents.
 21. An apparatus according to claim 15, wherein a pluralityof said reference plates are separately arranged in correspondence withthe visible and non-visible components, and said apparatus furthercomprises light-shielding means for shielding radiation of light on areference plate other than a reference plate corresponding to a lightcomponent to be radiated via said filter means.
 22. An apparatusaccording to claim 15, further comprising input means for inputting datafor canceling said discrimination means.
 23. An image processingapparatus which comprises illumination means for illuminating an image,and detection means for detecting non-visible light obtained from theimage in accordance with light radiated from said illumination means andfor generating a signal in accordance with the detected non-visiblelight, further comprising:a memory for storing a two-dimensional patternsignal for recognizing a specific image; and discrimination means fordiscriminating a specific original by comparing the signal generated inaccordance with the detected non-visible light with the two-dimensionalpattern signal read out from said memory.
 24. An apparatus according toclaim 23, wherein a plurality of kinds of the two-dimensional patternsare stored in accordance with angles of the image.
 25. An apparatusaccording to claim 23, wherein said discrimination means discriminatesthe detection result of said detection means at a plurality of angles inaccordance with an angle of a predetermined original.
 26. An apparatusaccording to claim 23, wherein the non-visible light has a wavelengthdifferent from a wavelength of the radiated light.
 27. An apparatusaccording to claim 23, wherein said discrimination means performsdiscrimination on the basis of fuzzy inference.
 28. A method ofprocessing an image, which includes the steps of radiating light onto animage, and detecting non-visible light obtained from the image inaccordance with the radiated light and generating a signal in accordancewith the detected non-visible light, comprising the steps of:storing ina memory a two-dimensional pattern for recognizing a specific image; anddiscriminating the specific image by comparing the signal generated inaccordance with the detected non-visible light with the storedtwo-dimensional pattern.